[PATCH net-next 18/24] net: Freescale: Use nested-BH locking for XDP redirect.
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2023-12-15 17:10:41
Also in:
bpf, lkml
Subsystem:
dpaa2 ethernet driver, freescale enetc ethernet drivers, freescale imx / mxc fec driver, networking drivers, the rest · Maintainers:
Ioana Ciornei, Claudiu Manoil, Vladimir Oltean, Wei Fang, Clark Wang, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The per-CPU variables used during bpf_prog_run_xdp() invocation and later during xdp_do_redirect() rely on disabled BH for their protection. Without locking in local_bh_disable() on PREEMPT_RT these data structure require explicit locking. This is a follow-up on the previous change which introduced bpf_run_lock.redirect_lock and uses it now within drivers. The simple way is to acquire the lock before bpf_prog_run_xdp() is invoked and hold it until the end of function. This does not always work because some drivers (cpsw, atlantic) invoke xdp_do_flush() in the same context. Acquiring the lock in bpf_prog_run_xdp() and dropping in xdp_do_redirect() (without touching drivers) does not work because not all driver, which use bpf_prog_run_xdp(), do support XDP_REDIRECT (and invoke xdp_do_redirect()). Ideally the minimal locking scope would be bpf_prog_run_xdp() + xdp_do_redirect() and everything else (error recovery, DMA unmapping, free/ alloc of memory, …) would happen outside of the locked section. Cc: Alexei Starovoitov <ast@kernel.org> Cc: Clark Wang <xiaoning.wang@nxp.com> Cc: Claudiu Manoil <claudiu.manoil@nxp.com> Cc: Ioana Ciornei <ioana.ciornei@nxp.com> Cc: Jesper Dangaard Brouer <hawk@kernel.org> Cc: John Fastabend <john.fastabend@gmail.com> Cc: Madalin Bucur <madalin.bucur@nxp.com> Cc: NXP Linux Team <redacted> Cc: Shenwei Wang <shenwei.wang@nxp.com> Cc: Vladimir Oltean <vladimir.oltean@nxp.com> Cc: Wei Fang <wei.fang@nxp.com> Cc: bpf@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- .../net/ethernet/freescale/dpaa/dpaa_eth.c | 1 + .../net/ethernet/freescale/dpaa2/dpaa2-eth.c | 1 + .../net/ethernet/freescale/dpaa2/dpaa2-xsk.c | 30 ++++++++++--------- drivers/net/ethernet/freescale/enetc/enetc.c | 1 + drivers/net/ethernet/freescale/fec_main.c | 1 + 5 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
index dcbc598b11c6c..8adc766282fde 100644
--- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
+++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c@@ -2597,6 +2597,7 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct qm_fd *fd, void *vaddr, } #endif + guard(local_lock_nested_bh)(&bpf_run_lock.redirect_lock); xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp); /* Update the length and the offset of the FD */
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 888509cf1f210..08be35a3e3de7 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c@@ -442,6 +442,7 @@ static u32 dpaa2_eth_run_xdp(struct dpaa2_eth_priv *priv, xdp_prepare_buff(&xdp, vaddr + offset, XDP_PACKET_HEADROOM, dpaa2_fd_get_len(fd), false); + guard(local_lock_nested_bh)(&bpf_run_lock.redirect_lock); xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp); /* xdp.data pointer may have changed */
diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c
index 051748b997f3f..e3ae9de6b0a34 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c@@ -56,23 +56,25 @@ static u32 dpaa2_xsk_run_xdp(struct dpaa2_eth_priv *priv, xdp_buff->rxq = &ch->xdp_rxq; xsk_buff_dma_sync_for_cpu(xdp_buff, ch->xsk_pool); - xdp_act = bpf_prog_run_xdp(xdp_prog, xdp_buff); + scoped_guard(local_lock_nested_bh, &bpf_run_lock.redirect_lock) { + xdp_act = bpf_prog_run_xdp(xdp_prog, xdp_buff); - /* xdp.data pointer may have changed */ - dpaa2_fd_set_offset(fd, xdp_buff->data - vaddr); - dpaa2_fd_set_len(fd, xdp_buff->data_end - xdp_buff->data); + /* xdp.data pointer may have changed */ + dpaa2_fd_set_offset(fd, xdp_buff->data - vaddr); + dpaa2_fd_set_len(fd, xdp_buff->data_end - xdp_buff->data); - if (likely(xdp_act == XDP_REDIRECT)) { - err = xdp_do_redirect(priv->net_dev, xdp_buff, xdp_prog); - if (unlikely(err)) { - ch->stats.xdp_drop++; - dpaa2_eth_recycle_buf(priv, ch, addr); - } else { - ch->buf_count--; - ch->stats.xdp_redirect++; + if (likely(xdp_act == XDP_REDIRECT)) { + err = xdp_do_redirect(priv->net_dev, xdp_buff, xdp_prog); + if (unlikely(err)) { + ch->stats.xdp_drop++; + dpaa2_eth_recycle_buf(priv, ch, addr); + } else { + ch->buf_count--; + ch->stats.xdp_redirect++; + } + + goto xdp_redir; } - - goto xdp_redir; } switch (xdp_act) {
diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index cffbf27c4656b..d516b28815af4 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c@@ -1578,6 +1578,7 @@ static int enetc_clean_rx_ring_xdp(struct enetc_bdr *rx_ring, rx_byte_cnt += VLAN_HLEN; rx_byte_cnt += xdp_get_buff_len(&xdp_buff); + guard(local_lock_nested_bh)(&bpf_run_lock.redirect_lock); xdp_act = bpf_prog_run_xdp(prog, &xdp_buff); switch (xdp_act) {
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index c3b7694a74851..335b1e307d468 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c@@ -1587,6 +1587,7 @@ fec_enet_run_xdp(struct fec_enet_private *fep, struct bpf_prog *prog, int err; u32 act; + guard(local_lock_nested_bh)(&bpf_run_lock.redirect_lock); act = bpf_prog_run_xdp(prog, xdp); /* Due xdp_adjust_tail and xdp_adjust_head: DMA sync for_device cover
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2.43.0